Electromagnetic reciprocating tool.



No. 72 0,596. PATENTED FEB. 17, 1903 O. MARSHALL. ELECTROMAGNETIC REGIPROGATING TOOL.

' APPLICATION IILED JUNE 8, 1901. RENEWED JULY 18, 1902.

I0 MODEL.

UNITED STATES PATENT OFFICE.

OLOYD MARSHALL, OF LAFAYETTE, INDIANA, ASSIGNOR TO JAMES S. ANDREYVS, OF ST. LOUIS, MISSOURI, AND l/VILLIAM M. SIMPSON, OF

CHICAGO, ILLINOIS.

ELECTROMAGNETIC RECIPROCATING TOOL.

SPECIFICATION forming part of Letters Patent No. 720,596, dated February 1'7, 1903.

Application filed June 8,1901. Renewed July 18, 1902. Serial No. 116,074. (No model.)

To to whont it 7na, z concern:

Be it known that I, OLoYn MARSHALL, a citizen of the United States, residing at Lafayette, in the county of Tippecanoe and State of Indiana, have invented certain new and useful Improvements in Electromagnetic Reciprocating Tools, of which the following is a specification.

This application has relation to reciprocating tools, and particularly to an electromagnetic tool for hammering, chipping, riveting, and similar purposes.

One object of the invention is to provide a commutating device outside of the tool and operating to alternately energize the solenoids by which the tool is reciprocated andautomatically and momentarily short-circuit each solenoid at the instant its circuit is broken to discharge the current'in the solenoid due to self-induction.

Another object of the invention is to inclose the plunger entirely within the shell or casing of the tool and provide openings in the casing communicating with the plunger-chamber to permit the circulation of air around the solenoids and to and from the plunger-chamber.

With these and other objects in view the invention consists in the novel construction and arrangement of parts hereinafter described, and illustrated in the accompanying drawings, in which Figure 1 is a longitudinal sectional view of the tool, showing the plunger ready to deliver a blow upon the tool. Fig. 2 is a side view of the commutator device.

Referring to the drawings, in which like numerals of reference denote corresponding parts in both the figures, 5 and 6 designate the two aXially-alined solenoids, which consist of coils of insulated wire wound on nonmagnetic sleeves 7 and 8. Each of the solenoids is inclosed within a shield of magnetic material consisting of the cylinders 10 11 and the outer heads 12 and. the inner heads 13, the heads being arranged at the ends of the solenoids and Within the cylinders.

The plunger 14, which is preferably made of soft wrought iron or steel, is arranged to travel Within the sleeves 10 11, and its inner end is reduced to receive a spring 15 and provided with a pointed or cone-shaped end 16 to enter a corresponding socket 17 in the head. The outer end 18 of the plunger is reduced to fit a similar socket 19 in the head 12.

The two shielded solenoids are separated from each other mechanically and electrically by a non-magnetic connection consisting of a cylinder 20.

a A handle 21 is provided at one end of the tool. At the other end the drill or chisel or hammer or other tool 22 is arranged in an opening 23 in the head 12 to receive a blow direct from the plunger. The solenoids are alternately energized by the operation of the commutating device, so that the retractingsolenoid 6 will carry the plunger back to its retracted position and compress the spring 15, as shown in Fig. 1, whereupon the circuit to solenoid 6 is broken and the working solenoid '5 is energized to carry the plunger forward to deliver the blow, this operation of the working solenoid being preferably assisted by the spring 15. The commutating device consists of the disks 24 25 26, mounted on a shaft 27, carrying a belt-wheel 28 and operated in any desired manner. The disks are made of insulating material, and disk 24 is provided on its periphery with a short metal strip 29, with which the brushes 3O 31 and 32 33 are arranged to make alternate contact. The disk 25 is provided on its periphery with a continuous metal contactstrip 34, and the disk 26 is provided with a metal contact-strip 35, which extends halfway around its periphery and is connected with the contact 34 on disk 25 by the block 36. The brush 37 is connected with the main wire 38 and is constantly in engagement with the strip 34 on the disk 25, and the brushes 39 40, connected, respectively, with the solenoids 5 and 6, are in alternate engagement with the contact-strip on disk 26. A resistance 41 is provided in one of the main Wires. It will thus be observed that one of the main wires is connected with the brush 37 and always in engagement with the constant contact 34:, which is in alternate circuit with the solenoids through the medium of the contacts 35 36 and the brushes 39 40. The other main wire 42 is connected in circuit with each of the solenoids, and the solenoid 5 is connected by a wire 43 with the brushes 39 33, and the solenoid 6 is connected by wire 44: with the brushes 40 31. The brushes 32 30 are connected by wire 45 with the main wire 42. The drawings show the workingsolenoid 5 energized, the spring compressed, and the plunger in retracted position and just starting forward to deliver a blow, the retracting-solenoid 6 being deenergized by reason of the movement of the contact 35 out of engagement with the brush 40 and into engagement with the brush 39 to energize the working solenoid. The retracting-solenoid is also short-circuited at this time by the engagement of the brushes 30 31 with the contact 29. YVhen the disks have revolved a half-turn, the contact 35 will pass from engagement with the brush 39 to break the circuit to the working solenoid 5 and into engagement with the brush 40 to close the retracting-solenoid circuit, the contact-strip 29 being then in engagement with the brushes 32 33 to momentarily short-circuitthe Working solenoid at the instant the contact-strip 35 passes from engagement with the brush 39.

The plunger is wholly inclosed within a chamber formed by the sleeves 7 8, the outer heads 12, and the cylinder 20. To permit the admission of air to said chamber and its escape therefrom during the reciprocation of the plunger, I provide passages 46, extending through the sleeves 7 and 8 and the solenoids and openings 47 in the cylinders 10 11. Besides allowing air to escape from one end of the plunger-chamber and enter the other end thereof as the plunger reciprocates I thereby provide a constant circulation of air around the solenoids and within the shields thereof during the operation of the plunger, which to a very large extent reduces the heat generated in the solenoids, and thereby promotes the efficiency of the tool. The openings 47 may be arranged in any desired position and any number employed; but the pas-.

sages 46 are located approximately at the end of the stroke of the plunger in each direction, so that the air which is compressed at one end may wholly escape and be circulated around the adjacent solenoid while air is being drawn in through the openings in the shield of the other solenoid and around said solenoid and into the plunger-chamber to prevent the formation of a vacuum, this operation being reversed on the return of the plunger and repeated during each movement thereof.

I have shown in the drawings a plunger reciprocated by means of two alined solenoids and a spring 15 for assisting the working solenoid in projecting the plunger to deliver the blow as being the preferred form of construction; but it will be understood that the spring may be omitted or it may be otherwise arranged and also that other changes in the form and construction and arrangement of parts may be made without departing from the spirit or sacrificing the advantages of the invention.

Having thus fully described my invention, what I claim, and desire to secure by Letters Patent, is-

1. The combination with a plunger and a pair of solenoids for reciprocating the same, of an external rotary commutating device comprising a series of disks of different diameters and means for operating the same to alternately energize the solenoids and mornentarily shortcircuit each solenoid at the time its circuit is broken.

2. The combination with a plunger and a pair of solenoids for reciprocating the same, of an external rotary commutating device comprising a series of disks of different diameters, and means for operating said device to alternately energize the solenoids and momentarily short-circuit each solenoid at the time its circuit is broken, and a spring bearing upon the plunger to assist one of said solenoids in moving the plunger, substantially as described.

3. The combination with a plunger and a pair of solenoids for reciprocating the same, of an external rotary commutating device connected in circuits with the solenoids, said device comprising a series of revolving disks of different diameters, and contact devices arranged to alternately energize the solenoids and momentarily short-circuit each solenoid at the time its circuit is broken.

4. The combination with a plunger and a pair of solenoids for reciprocating the same, of a commutating device connected in circuits with the solenoids, said device comprising a series of revolving disks, one disk having a contact-strip on half of its periphery, another disk having a contact-strip entirely around its periphery and connected with said preceding contact-strip, a short contact-strip on another disk, and brushes arranged in the circuits to engage said contact-strips as the disks revolve to alternately energize the solenoids and momentarily short-circuit each solenoid at the time its circuit is broken.

5. The combination with a plunger and a ,pair of solenoids for reciprocating the same,

of a commutating device connected in circuits with the solenoids and comprising three revolving disks, brushes in the circuits engaging said disks, and contact devices on the disks, one of said devices having a constant contact with a main-line brush during the whole revolution of the disk, the contact device on another disk being connected with said constant contact and having engagement alternately throughout its revolution with brushes in the circuit with the two solenoids to alternately energize said solenoids, and another disk having a short contact device arranged to engage brushes in circuit with each solenoid at the time said solenoids are deenergized to short-circuit the solenoids.

6. The combination with a pair of alined solenoids and a plunger arranged to be reciprocatcd by and through the same, of an independent cylinder surrounding each solenoid, a non-magnetic connection for said cylinders, inner heads for the cylinders at the opposite ends of the solenoids and outer heads adjacent to the outer ends of the solenoids, one of said outer heads being provided with an opening to receive a tool at one end of the plunger-chamber and the other head closing the other end of the plunger-chamber, substantially as described.

7. The combination with a pair of alined solenoids and a plunger arranged to be reciprocated by and through the same, and having a conical end, of a cylinder surrounding each solenoid, a non-magnetic connection between the cylinders, inner heads for the cylinders arranged adjacent to the opposing ends of the solenoids, a cylinder-head at the outer end of one solenoid provided with an opening to receive a tool, and a cylinder-head at the outer end of the other solenoid provided with a coneshaped socket to receive the conical end of the plunger and thereby reduce the airgap, substantially as described.

S. The combination with a solenoid, of a plunger and means for operating the same through the solenoid, said solenoid being provided with a transverse air-passage leading to the plunger-chamber, substantially as and for the purpose described.

9. The combination with a pair of alined solenoids provided With a centrally-located closed plunger-chamber, of a plunger arranged to be reciprocated in said chamber by the solenoids, and air-passages at the ends of 

